Abstract: Results about the effects on separation of an aerofoil at high angle of attack by air jets producing streamwise vortex of alternating circulation and spanwise vortex fluctuating up and down above the surface are given.Combined effects of the above two kinds of jets are also investigated.The actions of the mentioned jets both cause the retardation of separation and earlier reattachment.The suitable design and arrangement of the jets gain reduction of 76% separation bubble length.